関連ワード:  bash check if variable is unset or empty    bash check if variable is not set or empty    bash check if variable is undefined or empty    bash check if variable is null or empty    bash check if variable is not null or empty    bash check if variable is empty string or null    shell check if variable is empty or null    bash script check if variable is empty or null    shell script check if variable is empty or null    bash test if variable is null or empty  
結果 : bash check if variable is unset or empty